Apparatus for recovering solvent



Jan. 30, 1923.,

A. S, O'NEIL. APPARATUS FOR RECOVERJNG SOLVENT 3 SHEETS-SHEET 1 Fl LED MAR. 9, I921 Jan. 30, 1923.

A. S. O'NElLv APPARATUS FOR RECOVERING SOLVENT.

3 SHEETS-SHEET 2 FI LED MAR,

amvewtoz Jan, 30, 1923.

A S. O'NEiL. APPARATUS FOR RECOVEFHNG SOLVENT.

3 .SHEETSSHEET 3 FILED MAR.

000000 OOOOQO OOOOO @wvantoz dw \"A Patented Jan. 39,1923.

UNHTEE TATES teaser earaur enema.

ARTHUR SAMUEL ONEIL, OF SPRINGFIELD, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERN CARTRIDGE COMPANY, A CORPORATION OF DELAWARE.

APPARATUS FOR RECOVERING SOLVENT.

Application filed March 9, 1921.

To allwhomitmay concern:

Be it known that I, ARTHUR SAMUEL ONEIL, residing at Springfield, in the county of Sangamon, State of Illinois, have invented certain new and useful Improvements in Apparatus for Recovering Solvent; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to an apparatus for drying material and for recovering the volatile solvent used as a vehicle for substances with which the material is treated to produce such products as, for example, artificial leather and other coated fabrics together with water-proofed or rubber goods.

Various forms of apparatus of this character have heretofore been contrived wherein the heating and cooling surfaces thereof, to effectevaporation and condensation of the solvent, are enclosed in juxtaposition in one container or chamber and constitute one unit. In such constructions the gaseous medium for absorbing the va orized solvent and conveying it to the coo ing surfaces is not positively or forcibly circulated through the system, but instead the difference in density between the hot and cold gas is relied upon entirely to set up and maintain the necessary circulation by convection. Though circulation so induced may continue substantially uninterruptedly where the evaporating and cooling devices are adjacent and in one enclosure, the rate of flow of the gas is subject to radical variations which cannot be controlled or regulated; moreover, the circulation by convection tends to lag to a degree which slows up the process beyond what is necessary to insure against too quick dryin with resulting cracking and pin-holes 1n the coating. Furthermore, in such apparatus the extent of the cooling surface in relation to the evaporating capacity cannot readily be adjusted without substantial reconstruction of the apparatus; and, with the juxtaposed location of the evaporating and cooling devices, the heat in the evaporating space of the apparatus cannot well be conserved without loss or reduction so that the residual heat therein may be eflective partly to reheat the gaseous medium.

Serial No. 450,896.

Other forms of prior constructions have been proposed wherein the cooling devices for liquit'ying the vaporized solvent, usually consisting of a coil of pipes having an inlet and an outlet for the circulation of cooling water, are situated outside of the evaporating chamber, andv the gaseous'medium or vehicle for conveyingithe vaporized solvent is forcibly circulated through the system by means of a fan.

In all these constructions, however, the means for preheating the gaseous medium to raise it approximately to the temperature of the. evaporating chamber before entering-the latter consists of a separate unit, commonly a coil of-steam pipes, which is either outside of or is contained in the same casing in juxtaposition to the evaporating chamber. 7

In the apparatus constituting the present invention, there is an evaporating chamber which is preferably made shallow to secure as high a concentration of solvent vapor as possible. Situated in this evaporating chamber are means for heating the chamber to bring the temperature up to that'required for vaporizing the solvent. These heating means are constructed and arranged so that they will serve not only to provide the necessary heat in the chamber to efi'ect vaporization, but also'to supply an excess ofheat to preheat the gaseous medium as it enters the evaporating chamber so that by the time the gas in its circulation reaches the surface of the material it will have attained the temperature of the chamber, and will thus be in condition more readily to dry the material and to absorb the vaporized solvent. This arrangement of heating device in the evaporating chamber makes it possible, especially where, as in the preferred construction, such means consist of a series of steam heated plates arranged longitudinally of the chamber, to readily provide means for regulating the heat supplied to the evaporating chamber at diiterent consequent reduction in cost of the apparatus.

Unlike prior constructions in which the gaseous medium is commonly introduced into the evaporating chamber so that it travels in a direction opposite to the travel of the material being dried and longitudinally thereof, the gas in the apparatus of this invention is circulated over the sur face of the material laterally to the direction of travel of the material. This results in a more efficient drying action and especially so since this arrangement lends itself readily to the provision of means for varying the flow of gas at different points along the evaporating chamber at a rate dependent upon the moisture content of the material as it passes through the evaporating chamber.

Where as in the preferred embodiment of the invention the gaseous medium is circulated crosswise of the material and both the heating of the evaporating chamber and the How of the gaseous medium therethrough are regulated, the most efiicient drying action and absorption of liberated solvent results. For example, the regulating means may be manipulated so that the greatest flow of the gas and the highest heat occur at the inlet end of the evaporating chamher for the material and for a distance say of one third its length from that end where the moisture content of the material will be greatest. Beyond this the flow of gas and heat would ordinarily be. reduced in acc'ordance with the requirements of drying and absorbtion of the solvent gas. Thus the drying action may be nicely regulated to proceed at just the proper speed, and the.

danger of cracking the coating or the formation of pin holes therein due to a too rapid drying action will be eliminated. Besides, by supplying just enough heat and air to meet the requirements a substantial economy is effected.

Preferably the cooling chamber for liquifying the vaporized solvent is situated outside of the evaporating chamber, and means are provided for connecting these two chambers to form a closed passage for confining the body of gas which remains substantially constant and is used over and over again. Also it is preferred to cause positive circulation of the gas through the passage by means such, for example, as a fan. Such means produce a steady, uniform circulation of the gas which may be regu lated by suitable devices as for instance valves or damperssituated in the conduits through which the gas passes to and from.

the evaporating and cooling chambers.

By positioning the cooling chamber outside the evaporating chamber, or in other words externally thereto in-the form of a separate unit, not only is the heat in the evaporating chamber conserved and the excess of heat required for preheating the gases consequently minimized. but the ratio of heating and cooling surfaces may be readily varied by the addition of further cooling units.

' In the specific embodiment of the invention described hereinafter the means situated in the evaporating chamber for heating the latter consist of a plate or series of plates having connections with suitable heating means such as a valve-controlled steam supply pipe. In this construction the evaporating chamber is so arranged that the cool gas from the cooling chamber, or condenser, which is connected to the evaporating chamber to form a closed passage for the gas, pass into the evaporating chamber through an inlet opening above the heating plates, circulating above the plates and then below them and over the surface of the material to absorb the vaporized solvent, finally issuing from the chamber through an opening below the inlet for the gases.

In the accompanying drawings illustrating the construction of the apparatus which is at present preferred.

1 is a View partly in elevation and partly in section of the apparatus;

Fig. 2 is a plan view thereof;

Fig. 3 is a section of the apparatus along the line 33 of Fig. 1; and

Fig. 4 is a section of the apparatus along the line 4-1 of Fig. l.

The apparatus consists of an-evaporating chamber 1 through which the material to be dried passes and which, together with the appliance for coating the material, and the mechanism for moving it through the 100 evaporating chamber constitutes one unit;

a cooling chamber 2 comprising a unit sepa rate from the evaporating unit, and mechanical means for inducing a forced circulation of the drying gas through the 105 evaporating and cooling units.

The evaporating chamber; has a floor 2 resting on cross pieces 3, which in turn are supported by stringers {ljoined to upright members 5, the stringers and cross pieces 110 being suitably "braced as at Sand 7 respectively. Fastened to'the upright members and stringers are the longitudinally extending pieces 8 constituting the sides of the evaporating chamber, and. the top cover 9 115 thereof is braced by laterally and longitudinally disposed members 10.

Mounted in the evaporating chamber and directly over the floor thereof are rollers 11 which support the web of material 12 to be 120 dried. This material may consist of paper or textile fabric to which a coating is applied from the roller 13 over a number of tension rollers 14, through the evaporating chamber 1, thence over the roller 15 situated at the opposite end of the apparatus, then on to an endless conveyor 16 and finally from the endless conveyor to a rewinding roller 17. The rollers 13, 14 and 17 and also one pulley of the' endless conveyor 16, are supported on the frame 18; the roller 15 and the other pulley of the endless conveyor are supported on a frame 19 at the opposite end of the apparatus. Also mounted on the frame 18 are suitable means 20 for applying the coating solution to the material prior to its passing through the evaporating chamber. The endless conveyor lt asshown, consists. of a belt 21 passing over pulleys at opposite ends of the apparatus and mounted on the frame 18 and 19, as specified, and tension rollers 22 are provided for tightening the belt 21.

Supported in the evaporating chamber 1, as by means of brackets 23, is a plurality of heating plates 24 extending longitudinally of the evaporating chamber from one end thereof to the other. These plates are hollow, as shown, and have inlet -and outlet connections 25 and 26, respectively,for the circulation of steam therethrough, the steam supp-1y being controlled by'means of a valve 27. Leading into one side of the evaporating chamber is a plurality of pipes 28, having dampers 29 therein, which connect the chamber with a conduit 30. The latter has a downwardly extending portion 31 leading into a fan casing 32 in which is mounted a fan (not shown). Also connected to the fan casing is a conduit 33 which is connected by means of a plurality of pipes 34, having dampers therein, with a cooling chamber 3. The fan casing and conduits are suitably mounted on a frame 36 supported on a base 37.

Running the entire length of the evaporat-- ing chamber 1 is a plate 38, angular-1y disposed therein and connected at one side to the top of the heating plates 24, and at the other to the side wall of the chamber. This plate directs the air pa$ing into the chamber through pipe 28 upwardly to the top thereof and over the heating plates, and a perforated plate 39 is angularly positioned acrossthe passage formed by the plate 38 and the walls ofithe chamber to exclude the entrance into the evaporating chamber of any solid matter suspended in the air. The outlet from the evaporating chamber for the air saturated with solvent is located at 40 in the same'side wall as the inlet pipes 28 and at a point therein below the inlet pipes, and leads into a member 41 connecting the evaporating chamthe upper end of the condensing unit 2.

The condensing unit consists of an enclosed chamber 42 having therein a plurality of cooling pipes 43 connected at the inlet end through a valve 44, with a supply pipe 45 carrying the cooling solution, and at the The top covering 9 of the evaporating chamber has one or more openings, such as is shown at 50, provided with a movable cover, 51 having-water seals 52 at its sides which rest on the top edges of the evaporating unit. This cover may be removed to inspect the fabric passing through the evaporating chamber, and the water seals 52 insure a tight fit of the cover when replaced to exclude any air from entering the chamber.

The operation "of the device has, for the most part, already been ,indicated in the foregoing description.

The web of material 12 passes from roll 13 over tension rolls 14 and through the device 20 which applies the coating to the material. The web then passes through the evaporating chamber 1 to the rewinding mechanism, the web bein finally wound upon the roller 17. From this roller the web maybe led over some of the tension rollers and again passed through the same cycle of operation.

The evaporating chamber 1,'the condensor 2 and the member 41 connecting the two form a closed passage for confining the air-"which is circulated therethrough to dry the web of material 12 as it passes through the evaporating chamber 1 and to absorb and convey the solvent, vaporized by the heat in this chamber, to the condensor 2 through the connecting member 41. In the condensor 2 the air, saturated with the solvent comes in contact with the cooling pipes 43, the solvent vapor is condensed and descends through the outletpipe 48 to a suitable receptacle. The

the evaporating chamber 1 through the per-' forated plate 39, the airbeing deflected upwardly by the inclined plate 38. In the upper part of the evaporating chamber 1, the air comes in contact with the residual heat in" the evaporating chamber and with the heating plates 24, and finall passes around the plates to their under side and transversely over the web of material 12, thus completporized solvent.

ing the cycle. It will be evident that during the operation of the apparatus it is unnecessary to introduce any air from the outside and that the air which is originally confined within the apparatus may be used over and over, again. The circulation of air through the system is maintained by the fan mounted in the fan casing 32 which insures a steady, uniform flow of the air. The rate of flow through the system may be regulated by manipulating the dampers'29 in pipes 28, and the dampers 35 in pipes 34: as will be understood. By means of these dampers the rate of flow of the air can be readily adjusted so as to prevent a. too rapid drying action such as would cause the coating of the fabric to crack or otherwise result in the marring of the surface also the rate of flow of the air can be regulated to secure a greater flow toward the end of the evaporating chamber in which the material enters, and for a distance of about one third its length from this end where the material will hold the greatest amount of moisture. To secure these results the inletopenings for air along this part of the evaporating chamber may if necessary be larger than the remaining openings. Also by means of the valve 27 the amount of steam admitted to the heating plates 24 may be varied to secure the proper distribution along the length of the chamber, the heat intensity being regulated at a maximum for a distance of approximately one third of the length of the chamber from the inlet opening for the material. In this way, the highest heat can be supplied to the portion of the chamber where the moisture content of the material is greatest to enhance the drying and absorbing action, the amount of heat being gradually reduced toward the outlet of the chamber to correspond to the gradual drying of the material as it travels toward the outlet. Thus a substantial saving is expected in the amount of heat used.

By prbviding the heating plates 24 in the shallow evaporating chamber 1, where they serve both to heat the chamber to a temperature necessary to evaporate the solvent and to supply an excess of heat to preheat the air,v and also by separating the condenser from the heating unit making it a separate unit connected to the eve orating chamber so as to form a close passage for the air, it is possible to obtain an atmosphere of hi h concentration of Van fact, in the operation of the apparatus the circulating air is at all times at least saturated with the solvent at the different temperatures which it assumes in its circulation through the system and in-this way the formation of an explosive mixture is avoided. Explosions in apparatus of this characterare caused by static electricity produced by the drag of meats? the webbing of material being coated over the various supports in the machine. It then the atmosphere of the machine is below saturation point it frequently happens that an explosive mixture is formed which is ignited by sparks of electricty. In addition to the fact that in the present apparatus the solvent laden air is at all times saturated, in which condition it cannot form an'explosive mixture, it is also true that no explosion could take place at the beginning of the operation since there is always a pocket of solvent in the condensing unit, and so when the fan is started the solvent circulates through the apparatus until the air is saturated therewith.

I claim:

1. An apparatus of the character described having an evaporating chamber in which are means for supporting a web of material and for carrying it therethrough and means for heating the chamber, a cooling chamber, .means for circulating a gas eous medium through said evaporatin chamber over the material and through the cooling chamber to absorb the solvent vaporized in said evaporating chamber and to carry it to the cooling chamber to be liquified, said heating means situated in the evaporating chamber serving both to heat the chamber to effect vaporization of the solvent and to supply an excess of heat to preheat the gaseous medium upon its entrance to the evaporating chamber and before passing over the material.

2. An apparatus of the character de scribed having an evaporating chamber 'in which are means for supporting a web 'of material and for carrying it therethrough and means for heating the chamber, a cooling chamber, means for circulating a gaseous medium through said evaporating chamber laterally over the surface of the material and through the cooling chamber to absorb the solvent vaporized in said evaporating chamber and to carry it to the cooling chamber to be liquified, said heating means situated in the evaporating chamber serving both to heat the chamber to effect vaporization of the solvent and to supply an excess of heat to preheat the gaseous medium upon its entrance to the evaporating chamber and before passing over the material.

3. An apparatus of the character described having an evaporating chamber in which are means for supporting a web of material and. for carrying it therethrough and means for heating the chamber, a cooling chamber situated outside the evaporating chamber, means for connecting the evaporating and cooling chambers to form a closed passage for confininga body of gas, means for creating a forced circulation of the gas through said passage to absorb the solvent vaporized in the evaporating chamber and to carry it to the cooling chamber to be liquified, said heating means situated in the evaporating chamber serving both to heat the chamber to efi'ect vaporization of the solvent and to supply an excess of'heat to preheat the gaseous medium upon its entrance to the evaporating chamber and before passing over the material.

4. An apparatus of the character described having an evaporating chamber in which are means for supporting a web of material and for carrying it therethrough and means for heating the chamber, a cooling chamber, said evaporating and cooling chambers forming a closed passage for confining a body of gas, means for circulating the gas over the heating means in the evaporating chamber to preheat the gas, then over the material to absorb the vaporized solvent and finally to the cooling chamber to be liquified, and means for controlling the rate of fiow of the gas through said closed passage.

5. An apparatus of the character described having an evaporating chamber in which are means for supporting a Web of material and for carrying it therethrough and means for heating the chamber, a cooling chamber, said evaporating and cooling chambers forming a closed passage for confining a body of gas, means for circulating the gas over the heating means in the evaporating chamber to preheat the gas, then over the material to absorb the vaporized solvent and finally to the coolin chamber to be liquified, means for controdling the rate of flow of the gas through said closed passage, and means for varying the amount of heat supplied at different points along the evaporating chamber.

6. In anapparatus of the character described, a shallow evaporating chamber having means therein for supporting a web of material, a plate in said chamber, means for heating said plate, a condensor situated outside the evaporating chamber, means connecting the evaporating chamber and condensor to form therewith a closed passage for confining a body of gas, and devices for creating a forced circulation of the gas through the passage, said evaporating chamber being constructed and arranged so that the cooled gas enters the chamber above the heating plates, circulatesabove and below said plates and over the material and issues from the chamber through an opening below the inlet opening therefor.

7. In an apparatus of the character described, an evaporating chamber having means therein for supporting a web of material, a cooling chamber forming with the evaporating chamber a closed passage for con ning a body of gas, means for heating the evaporating chamber, means for regulating the amount of heat supplied to the evaporating chamber at different points thereof, and devices for creating a forced circulation of the gas through the passage.

8. In an apparatus of the character described, an evaporating chamber having means therein for supporting a web of material, a cooling chamber forming with the evaporating chamber a closed passage for confining a body of gas, means for heating the evaporating chamber, means for regulating the amount of heat supplied to the evaporating chamber at different points thereof, devices for creating a forced circulation of the gas through the passage, and means for regulating the circulation of the gas through the evaporating chamber.

9. In an apparatus of the character described, an evaporating chamber having means therein for supporting a Web of material, a cooling chamber forming with the evaporating chamber aclosed passage for confining a body of gas, a plurality of'heat ing plates extending longitudinally of the evaporating chamber, means for supplying steam to, said plates, valves for controlling the amount of steam supplied to the different plates, devices for creating a forced circulation of the gas through the passage, and dampers in said passage for regulating the flow of gas through the evaporating cham-' ber.

In testimony whereof I afiix my signature.

THUR SAMUEL ONEIL. 

